AU2014359034B2

AU2014359034B2 - Agitator impeller arrangement

Info

Publication number: AU2014359034B2
Application number: AU2014359034A
Authority: AU
Inventors: Markus Lehtonen; Ville Strommer
Original assignee: Outotec Finland Oy
Current assignee: Outotec Finland Oy
Priority date: 2013-12-04
Filing date: 2014-11-26
Publication date: 2017-03-30
Anticipated expiration: 2034-11-26
Also published as: MX368639B; CN105992637B; NO3077093T3; ES2656478T3; EA030256B1; WO2015082761A1; FI125190B; CA2931920C; CN105992637A; AU2014359034A1; MX2016007037A; ZA201603992B; EP3077093B1; EP3077093A1; CL2016001308A1; EA201690917A1; CA2931920A1

Abstract

An agitator impeller arrangement (1) for dispersing gas into a slurry of solids and liquid, the arrangement comprising an impeller (6) having a plurality of agitating blades (8) mounted radially and equally spaced to the circular hub disc (7). Each agitating blade (8) comprises a lower vertical dispersion blade (9) located below the plane of the circular hub disc (7) parallel to the radius of the circular hub disc, said vertical dispersion blade (9) having a straight vertical outer edge (10) being close to a periphery (11) of the circular hub disc (7), an inner edge (12) which is close to the shaft (2) and a rounded edge (13) curving with a radius r between the outer edge and the inner edge, an upper vertical dispersion blade (14) located above the plane of the circular hub disc (7) and parallel to the radius of the circular hub disc, and an inclined suspension blade (15) located radially outside the periphery of the circular hub disc (7), at a first angle (a) in relation to the vertical direction and below the plane of the circular hub disc.

Description

1 2014359034 28 Feb 2017

AGITATOR IMPELLER ARRANGEMENT FIELD OF THE INVENTION

The present invention relates to an agitator impeller 5 arrangement for dispersing gas into a slurry of solids and liquid.

BACKGROUND OF THE INVENTION

In prior art there is known from US 4,548,765 an agi-10 tator impeller arrangement for dispersing gas into a slurry of solids and liquid. The arrangement comprises a rotating shaft having an upper end which is connected to a rotating means, and a free lower end. The arrangement also comprises an impeller which is connect-15 ed coaxially and centrally in relation to the central axis to the lower end of the rotating shaft. The impeller has a horizontal circular hub disc which is connected centrally and horizontally to the lower end of the rotating shaft. A plurality of agitating blades 20 are mounted radially and equally spaced to the circular hub disc. US 4,548,765 discloses that each agitating blade comprises a lower vertical dispersion blade located below 25 the plane of the circular hub disc parallel to the radius of the circular hub disc. The vertical dispersion blade has a straight vertical outer edge which is close to a periphery of the circular hub disc, an inner edge which is close to the shaft and a rounded 30 edge curving with a radius between the outer edge and the inner edge. The impeller further comprises an upper vertical dispersion blade which is located above the plane of the circular hub disc and parallel to the radius of the circular hub disc. The impeller further 35 comprises an inclined suspension blade located radially outside the periphery of the circular hub disc at a

8719096J (GHMatters) P103224.AU 2 2014359034 28 Feb 2017 first angle in relation to the vertical direction and below the plane of the circular hub disc.

Corresponding to the impeller of US 4,548,765 there 5 has been a commercial product marketed with a trademark OKTOP®2000. The performance characteristics of the OKTOP®2000 impeller are outstanding. It is an efficient impeller for dispersing gas in three phase system (gas, liquid and solid) . The problem is that 10 the known impeller is quite a complex structure with more than 20 parts assembled with 50 welds required to assemble the six agitating blades to the circular hub disc. Each agitating blade is assembled from four separate blade parts since the upper dispersion blade and 15 the lower dispersion blade are separate parts welded to the circular hub disc and the inclined suspension blade outside the periphery is welded to an arm which is welded to the circular hub. The complex structure causes high manufacturing costs. A large amount of 20 parts and welds also makes the quality control very difficult. A further problem is that the welded joints are vulnerable to fatigue cracking and corrosion.

SUMMARY OF THE INVENTION 25 According to an aspect, the invention provides an agitator impeller arrangement for dispersing gas into a slurry of solids and liquid. The arrangement comprises a rotating shaft having an upper end which is connected to a rotating means, and a free lower end. The ro-30 fating shaft has a central axis. The arrangement further comprises an impeller connected coaxially and centrally in relation to the central axis to the lower end of the rotating shaft. The impeller includes a horizontal circular hub disc connected centrally and 35 horizontally to the lower end of the rotating shaft, and a plurality of agitating blades mounted radially and equally spaced to the circular hub disc. Each agi-

8719096_1 (GHMatters) P103224.AU 3 2014359034 28 Feb 2017 tating blade comprises a lower vertical dispersion blade located below the plane of the circular hub disc parallel to the radius of the circular hub disc, said vertical dispersion blade having a straight vertical 5 outer edge being close to a periphery of the circular hub disc, an inner edge which is close to the axis of rotation and a rounded edge curving with a radius between the outer edge and the inner edge. Each agitating blade further comprises an upper vertical disper-10 sion blade located above the plane of the circular hub disc and parallel to the radius of the circular hub disc. Each agitating blade further comprises an inclined suspension blade located radially outside the periphery of the circular hub disc, at a first angle 15 in relation to the vertical direction and below the plane of the circular hub disc.

According to the invention the agitating blade is one integral piece of metal plate, the lower vertical dis-20 persion blade, the upper vertical dispersion blade and the inclined suspension blade being bent from a single metal plate blank.

The advantage of the invention is that it provides an 25 impeller with a simple structure and few parts. The impeller can be manufactured without welding and it has reduced manufacturing costs and improved quality. Further, the impeller has improved fatigue strength and a long lifetime. 30

In an embodiment of the invention, the agitating blade comprises a horizontal part located between the upper vertical dispersion blade and the lower vertical dispersion blade, and bolt holes arranged at the horizon-35 tal part for attaching the agitating blade to the circular hub disc with bolted joints.

8719096_1 (GHMatters) P103224.AU 4 2014359034 28 Feb 2017

In an embodiment of the invention, the agitating blade has an outer end and an inner end which is at a closer distance to the central axis than the outer end, the outer end and the inner end defining a length of the 5 agitating blade. The radial distance between the central axis and the outer end defines a radius of the impeller, which radius is a half of the diameter of the impeller. The length of the agitating blade is 0,35xD with tolerance ± 0,05D. 10

In an embodiment of the invention, the lower vertical dispersion blade has a height measured from a lower surface of the horizontal part which height is 0,175xD with tolerance ± 0,02D, wherein D is the diameter of 15 the impeller.

In an embodiment of the invention, the lower vertical dispersion blade has a width W which is 0,15xD with tolerance + 0,02D, wherein D is the diameter of the 20 impeller.

In an embodiment of the invention, the radius r of the curving rounded edge of the lower vertical dispersion blade is 0,lxD with tolerance ± 0,01D, wherein D is 25 the diameter of the impeller.

In an embodiment of the invention, the first angle ( ) of the inclined suspension blade is 45° with tolerance ± 5° . 30

In an embodiment of the invention, the upper vertical dispersion blade has a length corresponding to the length of the agitating blade.

35 In an embodiment of the invention, the upper vertical dispersion blade has a height measured from an upper surface of the horizontal part which height is 0,105xD

8719096J (GHMatters) P103224.AU 5 2014359034 28 Feb 2017 with tolerance ± 0,01xD, wherein D is the diameter of the impeller.

In an embodiment of the invention, the upper vertical 5 dispersion blade is at a second angle to the upper surface of the horizontal part, which second angle is 90° with tolerance ± 5°.

In an embodiment of the invention, the inclined sus-10 pension blade has a straight lower edge which at a third angle to an outer edge of the inclined suspension blade, said outer edge coinciding with the outer end of the agitating blade, and which third angle is 75° with tolerance ± 5°. 15

In an embodiment of the invention, the inclined suspension blade has a straight inner edge which is parallel to the outer edge. 20 In an embodiment of the invention, a gap is defined between the inner edge of the inclined suspension blade and the outer edge of the lower vertical dispersion blade, said gap having a width of 0, 025xD with tolerance ± 0,005xD, and a closed end located at a 25 lateral distance A which is 0,045xD with tolerance ± 0,005xD from a first trailing face of the lower vertical dispersion blade, wherein D is the diameter of the impeller . 30 In an embodiment of the invention, the upper vertical dispersion blade has a second trailing face and the lower vertical dispersion blade has a front face which is parallel to the second trailing face, and that the lateral distance B between the second trailing face 35 and the front face is 0, lxD with tolerance ± 0,01xD, wherein D is the diameter of the impeller.

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In an embodiment of the invention, the metal plate of the agitating blade has a thickness which is 0,01xD with tolerance 0,01xD / -0,005xD. 5 The impeller dimensioned according to the above- mentioned principles has improved mixing performance and high power number. In tests it has been shown that the impeller constructed with the principles of the present invention gives similar gas dispersion with 10 same power intake compared to OKTOP®2000. Further, it gives better solids suspension with same power intake compared to OKTOP®2000. Further, due to higher power number than OKTOP®2000 it gives same mixing perfor mance with lower tip speed. Thus, the impeller is sub-15 ject to less abrasion and erosion and longer lifetime can be expected. Also current scale-up criteria of OKTOP®2000 can be utilized with the impeller of the invention . 20 It is to be understood that the aspects and embodiments of the invention described above may be used in any combination with each other. Several of the as pects and embodiments may be combined together to form a further embodiment of the invention. 25

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate em-30 bodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Figure 1 shows is a vertical section of a reactor in 35 which the impeller arrangement according to one embodiment of the invention has been installed,

8719096_1 (GHMatters) P103224.AU 7 2014359034 28 Feb 2017

Figure 2 shows an axonometric view of the impeller arrangement of Figure 1 seen obliquely from above,

Figure 3 shows an axonometric view of the impeller ar-5 rangement of Figure 2 seen obliquely from below,

Figure 4 shows a plan view of the impeller arrangement of Figure 2 seen from above, 10

Figure 5 is an axonometric view of one agitating blade of the impeller arrangement shown in Figures 2 to 4,

Figure 6 shows a side view of the agitating blade of Figure 5,

Figure 7 shows an end view of the agitating blade of Figure 5, and

Figure 8 shows a detail E from Figure 4. 20

DETAILED DESCRIPTION OF THE INVENTION 30

Figure 1 shows a reactor 100 which is equipped with an agitator impeller arrangement 1 and a gas inlet 101 arranged under the impeller arrangement. The impeller arrangement 1 is configured to disperse gas discharged from the gas inlet 101 effectively into small bubbles and at the same time to maintain a pulverous solid in good suspension in a liquid solution and also to produce in the gas-solid-liquid suspension a strong, suspension maintaining, turbulent flow field which is downward in the center of the reactor and upward along its sides. The operation method is similar as that disclosed in US 4,548,765.

35 The agitator impeller arrangement 1 comprises a rotating shaft 2 having an upper end 3 which is connected to a rotating means 4, such as an electric motor di-8719096 1 (GHMatters) P103224.AU 8 2014359034 28 Feb 2017 rectly or via a transmission. The rotating shaft 2 has a free lower end 5. The central symmetry axis x of the shaft is vertical. An impeller 6 is connected coaxially and centrally in relation to the central axis x to 5 the lower end 5 of the rotating shaft 2.

The impeller 6 comprises a horizontal circular hub disc 7 which is connected centrally and horizontally to the lower end 5 of the rotating shaft 2. The impel-10 ler also comprises a plurality of agitating blades 8, is the shown example six blades 8 which are mounted radially and equally spaced to the circular hub disc 7. 15 The new structure of the impeller 6 contains only seven parts, the circular hub disc 7 and six blades 8. In assembly welding is not required at all which reduces manufacturing costs up to 90%. Total cost of impeller is about 50 % compared to the conventional 20 OKTOP®2000 design. The fatigue strength is very high.

As can be seen from Figures 2 to 4, all agitating blades are identical. As best seen in Figure 3, each blade 8 comprises a lower vertical dispersion blade 9 25 which is located below the plane of the horizontal circular hub disc 7 and parallel to the radius of the circular hub disc 7.

Referring to Figures 3 and 6, the vertical dispersion 30 blade 9 has a straight vertical outer edge 10 close to a periphery 11 of the circular hub disc 7, an inner edge 12 which is close to the axis of rotation x and a rounded edge 13 curving with a radius r between the outer edge 10 and the inner edge 12. Referring to Fig-35 ures 2, 3, 5, 6 and 7, an upper vertical dispersion blade 14 is located above the plane of the circular hub disc 7 and parallel to the radius of the circular

8719096_1 (GHMatters) P103224.AU 9 2014359034 28 Feb 2017 hub disc. An inclined suspension blade 15 is located radially outside the periphery of the circular hub disc 7, at a first angle in relation to the vertical direction and below the plane of the circular hub disc 5 The agitating blade 8 is one integral piece of metal plate, the lower vertical dispersion blade 9, the upper vertical dispersion blade 10 and the inclined suspension blade 15 being bent from a single metal plate blank . 10

Referring to Figures 2 to 5, the agitating blade 8 comprises a horizontal part 16 which is located be tween the upper vertical dispersion blade 14 and the lower vertical dispersion blade 9. Bolt holes 17 are 15 arranged at the horizontal part 16 for attaching the agitating blade 8 to the circular hub disc 7 with bolted joints.

Referring to Figures 5 and 8, the agitating blade 8 20 has an outer end 18 and an inner end 19 which is at a closer distance to the central axis x than the outer end. The outer end 18 and the inner end 19 defining a length L of the agitating blade 8. The radial distance between the central axis x and the outer end 18 de-25 fines a radius R of the impeller 6, which is a half of the diameter D of the impeller. The length L of the agitating blade 8 is 0,35xD ± 0,05D.

Referring to Figure 7, the lower vertical dispersion 30 blade 9 has a height HL measured from a lower surface 20 of the horizontal part 16 which height HL is 0,175xD ± 0,02D.

Referring to Figure 8, the lower vertical dispersion 35 blade 9 has a width W which is 0,15xD ± 0,02D.

8719096J (GHMalters) P103224.AU 10 2014359034 28 Feb 2017

Referring to Figure 6, the radius r of the curving rounded edge 13 of the lower vertical dispersion blade 9 is 0,lxD ± 0,01D. 5 Referring to Figure 7, the first angle of the inclined suspension blade 15 is 45° ± 5°.

Referring to Figures 5 and 8, the upper vertical dispersion blade 14 has a length L corresponding to the 10 length L of the agitating blade 8.

Referring to Figure 7, the upper vertical dispersion blade 14 has a height Hu measured from an upper surface 21 of the horizontal part 16 which height Η0 is 15 0,105xD ± 0,OlxD.

Referring to Figure 7, the upper vertical dispersion blade 14 is at a second angle to the upper surface 21 of the horizontal part 16, which second angle is 20 90° ± 5°.

Referring to Figure 5, the inclined suspension blade 15 has a straight lower edge 22 which at a third angle to an outer edge 23 of the inclined suspension blade 25 15, said outer edge 23 coinciding with the outer end 18 of the agitating blade 8, and which third angle is 75° ± 5°. The inclined suspension blade 15 has a straight inner edge 24 which is parallel to the outer edge 23. 30

As shown in Figures 5 to 8, a gap G is defined between the inner edge 24 of the inclined suspension blade 15 and the outer edge 10 of the lower vertical dispersion blade 10. The gap G has a width s of 0, 025xD ± 35 0,005xD. The closed end 25 of the gap G is located at a lateral distance A, which is 0,045xD ± 0,005xD, from

8719096J (GHMatters) P103224.AU 11 2014359034 28 Feb 2017 a first trailing face 26 of the lower vertical dispersion blade 9.

As seen in Figure 7, the upper vertical dispersion 5 blade 14 has a second trailing face 27 and the lower vertical dispersion blade 9 has a front face 28 which is parallel to the second trailing face 27, and that the lateral distance B between the second trailing face 27 and the front face 28 is 0,lxD ± 0,01xD. The 10 metal plate of the agitating blade 8 has a thickness C which is 0,01xD + 0,01xD / -0,005xD.

As the above dimensions are all defined as being proportional to the diameter D of the impeller 6 (see 15 Figure 4) they are scalable according to the above disclosed principles.

Although the invention has been the described in conjunction with a certain type of impeller arrangement, 20 it should be understood that the invention is not limited to any certain type of impeller arrangement. While the present inventions have been described in connection with a number of exemplary embodiments, and implementations, the present inventions are not so 25 limited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of prospective claims.

In the claims which follow and in the preceding de-30 scription of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the 35 stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

8719096_1 (GHMatters) P103224.AU 12 2014359034 28 Feb 2017 10

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

8719096J (GHMallers) P103224.AU

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An agitator impeller arrangement for dispersing gas into a slurry of solids and liquid, the arrangement comprising - a rotating shaft having an upper end which is connected to a rotating means, and a free lower end, the rotating shaft having a central axis which is the axis of rotation, and an impeller connected coaxially and centrally in relation to the central axis to the lower end of the rotating shaft, said impeller having -- a horizontal circular hub disc connected centrally and horizontally to the lower end of the rotating shaft, and — a plurality of agitating blades mounted radially and equally spaced to the circular hub disc, each agitating blade comprising + a lower vertical dispersion blade located below the plane of the circular hub disc parallel to the radius of the circular hub disc, said vertical dispersion blade having a straight vertical outer edge being close to a periphery of the circular hub disc, an inner edge which is close to the axis of rotation and a rounded edge curving with a radius r between the outer edge and the inner edge, + an upper vertical dispersion blade located above the plane of the circular hub disc and parallel to the radius of the circular hub disc, and + an inclined suspension blade located radially outside the periphery of the circular hub disc, at a first angle in relation to the vertical direction and below the plane of the circular hub disc, wherein the agitating blade is one integral piece of metal plate, the lower vertical dispersion blade, the upper vertical dispersion blade and the inclined suspension blade being bent from a single metal plate blank.
2. The agitator impeller arrangement according to claim 1, wherein the agitating blade comprises - a horizontal part located between the upper vertical dispersion blade and the lower vertical dispersion blade, and - bolt holes arranged at the horizontal part for attaching the agitating blade to the circular hub disc with bolted joints.
3. The agitator impeller arrangement according to claim 1 or 2, wherein the agitating blade has an outer end and an inner end which is at a closer distance to the central axis than the outer end, the outer end and the inner end defining a length of the agitating blade; that the radial distance between the central axis and the outer end defines a radius of the impeller, which is a half of the diameter of the impeller; and that the length of the agitating blade is 0,35xD ± 0,05D, wherein D is the diameter of the impeller.
4. The agitator impeller arrangement according to any one of the claims 1 to 3, wherein the lower vertical dispersion blade has a height measured from a lower surface of the horizontal part which height is 0,175xD ± 0,02D, wherein D is the diameter of the impeller.
5. The agitator impeller arrangement according to any one of the claims 1 to 4, wherein the lower vertical dispersion blade has a width which is 0,15xD ± 0,02D, wherein D is the diameter of the impeller.
6. The agitator impeller arrangement according to any one of the claims 1 to 5, wherein the radius r of the curving rounded edge of the lower vertical dispersion blade is 0,lxD ± 0,01D, wherein D is the diameter of the impeller.
7. The agitator impeller arrangement according to any one of the claims 1 to 6, wherein the first angle of the inclined suspension blade is 45° ± 5°.
8. The agitator impeller arrangement according to any one of the claims 1 to 7, wherein the upper vertical dispersion blade has a length corresponding to the length of the agitating blade.
9. The agitator impeller arrangement according to any one of the claims 1 to 8, wherein the upper vertical dispersion blade has a height measured from an upper surface of the horizontal part which height is 0,105xD ± 0,01xD, wherein D is the diameter of the impeller.
10. The agitator impeller arrangement according to claim 9, wherein the upper vertical dispersion blade is at a second angle to the upper surface of the horizontal part, which second angle is 90° ± 5°.
11. The agitator impeller arrangement according to any one of the claims 1 to 10, wherein the inclined suspension blade has a straight lower edge which at a third angle to an outer edge of the inclined suspension blade, said outer edge coinciding with the outer end of the agitating blade, and which third angle is 75° ± 5°.
12. The agitator impeller arrangement according to any one of the claims 1 to 11, wherein the inclined suspension blade has a straight inner edge which is parallel to the outer edge.
13. The agitator impeller arrangement according to claim 12, wherein a gap is defined between the inner edge of the inclined suspension blade and the outer edge of the lower vertical dispersion blade, said gap having a width (s) of 0,025xD ± 0,005xD, and a closed end located at a lateral distance which is 0,045xD ± 0,005xD from a first trailing face of the lower vertical dispersion blade, wherein D is the diameter of the impeller.
14. The agitator impeller arrangement according to any one of the claims 1 to 13, wherein the upper vertical dispersion blade has a second trailing face and the lower vertical dispersion blade has a front face which is parallel to the second trailing face, and that the lateral distance B between the second trailing face and the front face is 0,lxD ± 0,01xD, wherein D is the diameter (D) of the impeller.
15. The agitator impeller arrangement according to any one of the claims 1 to 14, wherein the metal plate of the agitating blade has a thickness which is 0,01xD + 0,01xD / -0, 005xD, wherein D is the diameter (D) of the impeller.